Aerodynamic pressure-wave machine

ABSTRACT

An aerodynamic pressure-wave machine which includes a stator and a celled rotor, the stator being provided with gas inlet and outlets adjoining one side of the rotor at one end of the rotor cells and air inlets and outlets adjoining the opposite side of the rotor at the opposite end of the rotor cells. The stator also includes a compression recess located after the air inlet, as viewed in the direction of rotation of the cells, and a web located in the gas outlet. This web extends radially for the entire height of the gas outlet and its width is approximately the same as one of the rotor cells. The function of the web is to cause pressure waves to impinge upon the compression recess at the highest and lowest speeds within the greatest part of the operating range of the machine.

United States Patent 1 Croes 3,776,663 Dec. 4, 1973 AERODYNAMIC PRESSURE-WAVE MACHINE [75] Inventor: Nicolaus Croes, Niederrohrdorf,

Switzerland [73] Assignee: Brown Boveri & Company Limited, Baden, Switzerland [22] Filed: Aug. 29, 1972 [21] Appl. No.: 284,764

Primary Examiner-C. J. Husar Assistant ExaminerLeonard Smith Attorney-Ralph B. Parker et al.

[5 7 ABSTRACT An aerodynamic pressure-wave machine which includes a stator and a celled rotor, the stator being provided with gas inlet and outlets adjoining one side of the rotor at one end of the rotor cells and air inlets and outlets adjoining the opposite side of the rotor at the opposite end of the rotor cells. The stator also includes a compression recess located after the air inlet, as viewed in the direction of rotation of the cells, and a web located in the gas outlet. This web extends radially for the entire height of the gas outlet and its width is approximately the same as one of the rotor cells. The function of the web is to cause pressure waves to impinge upon the compression recess at the highest and lowest speeds within the greatest part of the operating range of the machine.

4 Claims, 4 Drawing Figures PATENTED DEC 4 I375 FIG-4 AERODYNAMIC PRESSURE-WAVE MACHINE The present invention relates to an aerodynamic pressure-wave machine of the type in which the gas inlet and the gas outlet are located on one side of the celled rotor, the air inlet and air outlet are located on the other side and wherein a compression recess is provided and located after the air inlet when viewed in the direction of rotation of the cells.

In aerodynamic pressure-wave machines, the arrangement of the edges is an important parameter which greatly influences the efficiency of compression and its dependence on the rotor speed. So that a pressure-wave machine can be used for a wide range of loads and speeds, e.g., as a means of charging an internal-combustion engine, recesses are employed on the air and/or gas sides (German Pat. No. 1,162,631).

Extensive investigations into optimum edge arrangements in pressure-wave machines for large throughputs have shown that pre-compression of the air is desirable at high speeds because otherwise the pressure in the air outlet is too low. At low speeds, but still within the operating range of the machine, such pre-compression, supplementary to the pre-compression already achieved by virtue of the principle of the compression recess, is undesirable because this has too great a retarding effect on the flow rate.

The principal object of the present invention is to achieve high-pre-compression of the air in the pressure-wave machine at high speeds, without unfavorably influencing the throughput at low speeds.

This object is achieved in that a web is located in the gas outlet in such a way that pressure waves emanating from this web over at least the greatest part of the operating range of the pressure-wave machine, and up to the highest speeds, impinge in the compression recess, and at the lowest speeds of the operating range impinge in the compression recess or on a wall between the compression recess and the air inlet.

The web in the gas outlet, which retards the gases striking it at high velocity, particularly at high rotor speeds, gives rise to pressure waves which propagate through the cells to the other side of the rotor and there impinge in the compression recess, whereupon they raise its pressure level and so allow pre-compression of the air drawn from the air inlet and present in the cells. The intensity of the pressure waves emanating from the web diminishes as the rotor speed decreases because the exit velocity of the gases also drops and hence the influence of the web on the process is similarly reduced. The web is located so far into the gas outlet,

viewed in the direction of rotation of the rotor, that even at the lowest speeds of the operating range the pressure waves emanating from the web do not pass into the air inlet, and therefore do not impede the intake of air.

The invention will now be explained in more detail with reference to the accompanying schematic drawing illustrating a preferred embodiment wherein:

FIG. 1 is a developed projection of the rotor of the improved pressure wave machine together with the adjacent side portions of the stator;

FIGS. 2 and 3 are details from FIG. 1, and

FIG. 4 illustrates a variation of FIG. 3.

FIG. 1 shows the developed projection of the rotor l, of which only a few cells 2 are indicated, and which moves past the controlling edges of the stator in the direction shown by the arrow. The side portions of the stator contain at one side of the rotor, i.e., at one end of the rotor cells the gas inlet 2v and the gas outlet 1n, and at the other side of the rotor the air inlet 1v the air outlet 2n and a compression recess 3 located after the air inlet as viewed in the direction of rotation of the cells.

In the rear portion of the gas outlet In is a web 4 which extends radially over the entire height of the outlet and is preferably of approximately the same width as one cell. The leaving gases flowing into the outlet impinge partly on the web 4, whereupon they are retarded, giving rise to a pressure increase which propagates as a pressure wave through the cell 2 to the other side of the rotor 1. Here, as shown in FIG. 2 for the highest speed occurring in the operating range of the pressure-wavemachine, this pressure wave impinges in the compression recess 3, thus causing precompression of the air.

As the speed decreases, the pressure waves emanating from web 4 become progressively flatter, but still always impinge in the compression recess 3. It is important that even at the lowest speeds in the operating range of the pressure-wave machine they should not impede the intake of air, as would be the case if the pressure waves were to pass into the air inlet 1v. The web 4 must therefore be so arranged that even at the lowest speeds the pressure waves emanating from it still impinge at least on the wall 5 between the compression recess 3 and air inlet 1v, as is shown in FIG. 3. If the compression recess 3 is somewhat larger in the direction of rotation, as indicated in FIG. 4, the web 4 can then be so arranged that the pressure waves still impinge in the compression recess 3 even at the lowest speeds.

The operating range of the pressure-wave machine here denotes that range of speeds within which the machine runs under normal operating conditions. The starting process of the machine, e.g., at low speeds beginning from zero, lies outside this range.

[claim 1. An aerodynamic pressure-wave machine comprising a stator, a celled rotor, said stator including a gas inlet and a gas outlet adjoining one side of said rotor at one end of the rotor cells, an air inlet and an air outlet adjoining the opposite side of said rotor at the opposite end of the rotor cells, a compression recess provided in said stator also adjoining said opposite end of said rotor and located after said air inlet as viewed in the direction of rotation of the cells, and a web provided by said stator and which is located in said gas outlet such that pressure waves emanating from said web over at least the greatest part of the operating range of said pressure-wave machine and up to the highest speeds within that range impinge upon said compression recess, and at the lowest speed with said operating range impinge upon said compression recess or on a wall portion of said stator located between said compression recess and said air inlet.

2. An aerodynamicpressure-wave machine as defined in claim 1 wherein the width of said web is approximately the same as one of the rotor cells.

3. An aerodymanic pressure-wave machine as defined in claim 1 wherein said web extends radially for the entire height of said gas outlet.

4. An aerodynamic pressure-wave machine as defined in claim 1 wherein said web extends radially for the entire height of said gas outlet and has a width which is approximately the same as one of the rotor cells.

* I t I 

1. An aerodynamic pressure-wave machine comprising a stator, a celled rotor, said stator including a gas inlet and a gas outlet adjoining one side of said rotor at one end of the rotor cells, an air inlet and an air outlet adjoining the opposite side of said rotor at the opposite end of the rotor cells, a compression recess provided in said stator also adjoining said opposite end of said rotor and located after said air inlet as viewed in the direction of rotation of the cells, and a web provided by said stator and which is located in said gas outlet such that pressure waves emanating from said web over at least the greatest part of the operating range of said pressure-wave machine and up to the highest speeds within that range impinge upon said compression recess, and at the lowest speed with said operating range impinge upon said compression recess or on a wall portion of said stator located between said compression recess and said air inlet.
 2. An aerodynamic pressure-wave machine as defined in claim 1 wherein the width of said web is approximately the same as one of the rotor cells.
 3. An aerodymanic pressure-wave machine as defined in claim 1 wherein said web extends radially for the entire height of said gas outlet.
 4. An aerodynamic pressure-wave machine as defined in claim 1 wherein said web extends radially for the entire height of said gas outlet and has a width which is approximately the same as one of the rotor cells. 